
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.font.FontRenderContext;
import java.awt.font.LineMetrics;
import javax.swing.JComponent;
import javax.swing.JFrame;





public class FontShow extends JComponent {
  public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

    Font font = new Font("Dialog", Font.PLAIN, 96);
    g2.setFont(font);
    int width = getSize().width;
    int height = getSize().height;

    String message = "Java2s";

    FontRenderContext frc = g2.getFontRenderContext();
    LineMetrics metrics = font.getLineMetrics(message, frc);
    float messageWidth = (float) font.getStringBounds(message, frc).getWidth();

    // center text
    float ascent = metrics.getAscent();
    float descent = metrics.getDescent();
    float x = (width - messageWidth) / 2;
    float y = (height + metrics.getHeight()) / 2 - descent;

    int PAD = 25;
    g2.setPaint(getBackground());
    g2.fillRect(0, 0, width, height);

    g2.setPaint(getForeground());
    g2.drawString(message, x, y);

    g2.setPaint(Color.white); // Base lines    
    drawLine(g2, x - PAD, y, x + messageWidth + PAD, y);
    drawLine(g2, x, y + PAD, x, y - ascent - PAD);
    g2.setPaint(Color.green); // Ascent line
    drawLine(g2, x - PAD, y - ascent, x + messageWidth + PAD, y - ascent);
    g2.setPaint(Color.red); // Descent line
    drawLine(g2, x - PAD, y + descent, x + messageWidth + PAD, y + descent);
  }

  private void drawLine(Graphics2D g2, double x0, double y0, double x1, double y1) {
    Shape line = new java.awt.geom.Line2D.Double(x0, y0, x1, y1);
    g2.draw(line);
  }

  public static void main(String args[]) {
    JFrame frame = new JFrame();
    frame.setSize(420, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new FontShow());
    frame.setVisible(true);
  }
}